cm:Table: us-gaap:ScheduleOfShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeTable
| Share-based Payment Arrangement, Option, Exercise Price Range [Table] |
| us-gaap:ScheduleOfShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeTable |
| Details comprising a table providing supplementary information on outstanding and exercisable share awards as of the balance sheet date which stratifies outstanding options by ranges of exercise prices. |
| cm:Table |
| Text/String (xbrli:stringItemType) |
| For Period (duration) |
| (no balance type) |
| true |
| us-gaap:ScheduleOfShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeTable |